JP2024024871A - electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of polarization of a battery in an electric vehicle which travels with electric power of the battery.

SOLUTION: An electric vehicle which uses a battery as a power source and a motor as a driving source, comprises a travel control device which adjusts travel speed. The travel control device repeatedly executes gentle acceleration travel and coasting travel alternatively if detecting a high load state of the battery, and increases and decreases the travel speed within a prescribed speed range interposing setting speed when traveling in constant speed by adjusting the travel speed to the setting speed.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to running control of an electric vehicle.

2. Description of the Related Art In recent years, constant speed driving control has been used on expressways and the like to cause a vehicle to travel at a constant speed at a set speed. In addition, in recent years, when a preceding vehicle is detected in front of the own vehicle using radar means, imaging means, or a combination of these radar means and imaging means, if the speed of the preceding vehicle is less than the set speed, a predetermined inter-vehicle distance may be increased. Cruise control control is used in which the vehicle follows the vehicle in front, and if the speed of the vehicle in front is faster than the set vehicle speed or the vehicle in front is not detected, the vehicle travels at a constant speed at the set vehicle speed ( For example, see Patent Document 1).

JP2017-65382A

Incidentally, in recent years, electric vehicles that use batteries as a power source and motors as a drive source have been used. When such an electric vehicle runs at high speed for a long period of time, the input/output current of the battery may be on the discharging side while the vehicle is running. In this case, the ions in the battery may be biased and polarized, increasing the internal resistance and increasing the amount of heat generated by the battery. Furthermore, this may lead to insufficient cooling capacity of the battery, leading to limitations on travel output, etc., or to deterioration of the battery.

Therefore, an object of the present invention is to suppress the occurrence of battery polarization in an electric vehicle that runs on battery power.

The electric vehicle of the present invention is an electric vehicle that uses a battery as a power source and a motor as a drive source, and includes a travel control device that adjusts a travel speed, and the travel control device adjusts the travel speed to a set speed. If a high load state of the battery is detected while driving at a constant speed, slow acceleration driving and coasting driving are repeated alternately, and the driving speed is maintained within a predetermined speed range sandwiching the set speed. It is characterized by increasing or decreasing.

In this way, by alternately repeating slow acceleration driving and coasting driving, it is possible to balance battery discharging and charging, suppressing battery input and output from being too much on the discharging side, and reducing battery polarization. The occurrence can be suppressed. Thereby, an increase in the amount of heat generated by the battery, deterioration of the battery, etc. can be suppressed.

In the electric vehicle of the present invention, the travel control device may execute constant speed travel at the set speed when detecting release of the high load state of the battery.

If the battery changes from a high load state to a low load state where almost no polarization occurs, even if the input and output of the battery are only on the discharge side, stop driving that alternates between slow acceleration and coasting. to return to constant speed driving. As a result, smooth constant speed running can be achieved in a low load state.

The electric vehicle of the present invention includes a current sensor that detects an output current value of the battery, and the travel control device is configured to detect when the square value of the output current value of the battery detected by the current sensor exceeds a first threshold value. If the high load state of the battery is detected, and the square value of the output current value becomes equal to or less than a second threshold value that is smaller than the first threshold value, the detection of the high load state of the battery is canceled. good.

This makes it possible to detect and release the high load state of the battery using a simple method.

The electric vehicle of the present invention includes: a current sensor that detects an output current value of the battery; and a voltage sensor that detects a voltage value of the battery; An output power value of the battery is calculated based on the output current value and the voltage value of the battery detected by the voltage sensor, and when the output power value exceeds a first reference value, the output power value of the battery is calculated. When a high load state is detected and the output power value becomes equal to or less than a second reference value that is smaller than the first reference value, release of the high load state of the battery may be detected.

This makes it possible to detect and release the high load state of the battery using a simple method.

The present invention can suppress the occurrence of battery polarization in an electric vehicle that runs on battery power.

FIG. 1 is a system diagram showing the configuration of an electric vehicle according to an embodiment. 2 is a map showing the relationship between the square value of the battery output current stored in the memory of the travel control device shown in FIG. 1 and the load state of the battery. FIG. 2 is a functional block diagram of the travel control device shown in FIG. 1. FIG. 2 is a flowchart showing a travel control operation of the electric vehicle shown in FIG. 1. FIG. 2 is a graph showing the running speed of the electric vehicle shown in FIG. 1 with respect to time and changes in battery input/output current. 2 is a map showing the relationship between the battery output power and the battery load state stored in the memory of the travel control device shown in FIG. 1. FIG.

As shown in FIG. 1, the electric vehicle 100 of the embodiment includes a battery 11, an inverter 12, a motor 15 as a drive source of the electric vehicle 100, and a travel control device 30.

The battery 11 is a power source that supplies DC power. The inverter 12 is connected to the battery 11, converts the DC power input from the battery 11 into three-phase AC power and supplies it to the motor 15, and also converts the three-phase AC power input from the motor 15 into DC power. to charge the battery 11. The inverter 12 converts power by turning on/off a plurality of internally provided switching elements. The driving force of the motor 15 is transmitted from the output shaft 16 of the motor 15 to the transaxle 18 via the gear 17 to drive the wheels 19 of the electric vehicle 100.

A current sensor 21 that detects an output current value IB of the battery 11 and a voltage sensor 22 that detects a voltage value VB of the battery 11 are arranged between the battery 11 and the inverter 12. Further, the high-voltage cable between the inverter 12 and the motor 15 includes a V-phase current sensor 23 that detects the V-phase current value Iv of the three-phase AC power, and a W-phase current sensor 24 that detects the W-phase current value Iw. is installed. Furthermore, a resolver 25 is attached to the output shaft 16 of the motor 15 to detect the rotational angular position θ of the output shaft 16. Further, a vehicle speed sensor 26 that detects the vehicle speed V of the electric vehicle 100 is attached to the transaxle 18 .

The travel control device 30 is a computer that includes a CPU 31, which is a processor that performs internal information processing, and a memory 32 that stores operating programs, control data, and the like. The driving control device 30 includes the output current value IB, voltage value VB, and V-phase output current value of the battery 11 detected by the current sensor 21, voltage sensor 22, V-phase current sensor 23, W-phase current sensor 24, resolver 25, and vehicle speed sensor 26. Current value Iv, W-phase current value Iw, rotation angle position θ of output shaft 16 of motor 15, and vehicle speed V are input. Further, the accelerator opening degree and the brake opening degree of the electric vehicle 100 are input to the driving control device 30 . Furthermore, the cruise control device 30 receives the cruise control ON/OFF signal from the cruise control switch, the set speed Vs for constant speed driving from the speed setting switch, and the speed and distance of the preceding vehicle from the preceding vehicle monitoring device. is input. The cruise control switch and the speed setting switch are attached to the steering wheel, for example, and the ON/OFF signal of the cruise control and the set speed Vs are inputted by the driver's operation of each switch. The preceding vehicle monitoring device may be, for example, a radar, or may be composed of a radar and a camera. The detailed configuration of the travel control device 30 will be explained later with reference to FIG. 3.

The travel control device 30 stores in the memory 32 a map 33 showing the relationship between the square value IB2 of the output current value IB of the battery ¹¹ and the load state of the battery 11 as shown in FIG. The map 33 detects a high load state of the battery 11 when the square value IB2 of the output current value IB of the battery ¹¹ detected by the current sensor 21 exceeds the first threshold value, and calculates the square value ^IB2 of the output current value IB. becomes equal to or less than a second threshold value, which is smaller than the first threshold value, the detection of the high load state of the battery 11 is canceled and the low load state of the battery 11 is detected. The high load state is a load state in which polarization may occur when the input and output of the battery 11 is only on the discharge side. The low load state is a load state in which almost no polarization occurs even when the input and output of the battery 11 is only on the discharge side.

Next, the detailed configuration of the travel control device 30 will be described with reference to FIG. 3. As shown in FIG. 3, the travel control device 30 includes four functional blocks: a cruise control section 35, a battery monitoring section 36, a gradual acceleration/deceleration control section 37, and an inverter control section 38. Each functional block can be realized by the CPU 31 shown in FIG. 1 executing a program stored in the memory 32.

The inverter control unit 38 stores the output current value IB of the battery 11, the voltage value VB, the V-phase current value Iv, the W-phase current value Iw, the rotation angle position θ of the output shaft 16 of the motor 15, the vehicle speed V, and the accelerator opening. , the brake opening degree is input. Based on these input data, the inverter control unit 38 generates an inverter drive command for turning on/off a plurality of switching elements provided inside the inverter 12 and outputs it to the inverter 12. The inverter 12 turns on/off a plurality of internally provided switching elements based on an inverter drive command input from the inverter control unit 38, converts DC power into three-phase AC power, and drives the motor 15. .

The cruise control unit 35 receives the cruise control ON/OFF signal, the set speed Vs for constant speed driving, the speed of the preceding vehicle, and the distance of the preceding vehicle. The cruise control section 35 generates a traveling speed signal based on these input data and outputs it to the inverter control section 38 and the slow acceleration/deceleration control section 37. When the cruise control unit 35 captures a preceding vehicle while the cruise control ON signal and the set speed Vs are input, the cruise control unit 35 opens a predetermined inter-vehicle distance and approaches the preceding vehicle when the speed of the preceding vehicle is less than the set speed Vs. Follow-up travel control is performed to cause the electric vehicle 100 to travel while following. Furthermore, when the ON signal of the cruise control and the set speed Vs are input, and the speed of the preceding vehicle is faster than the set speed Vs, or when the preceding vehicle is not captured, the electric vehicle 100 is moved at the set speed Vs. Performs constant speed driving control to drive at a constant speed. In the case of follow-up travel control, the cruise control section 35 outputs a variable speed according to the speed of the preceding vehicle to the inverter control section 38 and the gradual acceleration/deceleration control section 37 as a traveling speed signal. Further, in the case of constant speed traveling control, the cruise control section 35 outputs the set speed Vs to the inverter control section 38 and the gradual acceleration/deceleration control section 37 as a traveling speed signal. When the variable speed is input from the cruise control section 35, the inverter control section 38 generates and outputs an inverter drive command such that the vehicle speed V becomes the variable speed without using the accelerator opening or the brake opening. do. As a result, electric vehicle 100 follows the preceding vehicle at the variable speed input from cruise control unit 35 . When the set speed Vs is input from the cruise control unit 35, the inverter control unit 38 generates an inverter drive command so that the vehicle speed V becomes the set speed Vs without using the accelerator opening or the brake opening. and output it. As a result, electric vehicle 100 travels at a constant speed at set speed Vs.

The output current value IB and voltage value VB of the battery 11 are input to the battery monitoring unit 36 . The battery monitoring unit 36 calculates the square value ^IB2 of the input output current value IB of the battery 11, and uses the map 33 described with reference to FIG. 2 to determine whether the load state of the battery 11 is a high load state or a low load state. and outputs the detected state of the battery 11 to the gradual acceleration/deceleration control section 37 as a battery state signal.

When the traveling speed signal inputted from the cruise control section 35 is the set speed Vs and the battery status signal inputted from the battery monitoring section 36 is in a high load state, the gradual acceleration/deceleration control section 37 controls the set speed Vs and the inverter control. Based on the vehicle speed V input from the section 38, a slow acceleration running command or a coasting running command is generated and output to the inverter control section 38. When a slow acceleration running command or a coasting running command is input from the slow acceleration/deceleration control unit 37, the inverter control unit 38 uses the accelerator opening, the brake opening, and the running speed signal input from the cruise control unit 35. Based on the slow acceleration running command or the coasting running command input from the slow acceleration/deceleration control unit 37, an inverter drive command is generated to drive the inverter 12.

Next, the running operation of the electric vehicle 100 according to the embodiment will be described with reference to FIGS. 4 and 5.

As shown in step S101 in FIG. 4, the cruise control unit 35 determines whether a cruise control ON signal is input from the cruise control switch. If the determination in step S101 in FIG. 4 is NO, step S101 in FIG. 3 is repeatedly executed. When the cruise control unit 35 determines YES in step S101 of FIG. 4, it starts cruise control. The cruise control section 35 outputs the set speed Vs as a traveling speed signal to the gradual acceleration/deceleration control section 37 and the inverter control section 38 when performing constant speed traveling control, and outputs the set speed Vs as a traveling speed signal to the gradual acceleration/deceleration control section 37 and the inverter control section 38 when performing follow-up traveling control. The speed is output as a traveling speed signal to the slow acceleration/deceleration control section 37 and the inverter control section 38. Inverter control unit 38 generates an inverter drive command based on the traveling speed signal and outputs it to inverter 12 to cause electric vehicle 100 to travel at a constant speed or follow-up.

Slow acceleration/deceleration control section 37 determines whether electric vehicle 100 is traveling at a constant speed. If the set speed Vs is input as the traveling speed signal from the cruise control section 35, the gradual acceleration/deceleration control section 37 determines YES in step S102 of FIG. 4 and proceeds to step S103 of FIG. On the other hand, if the variable speed is inputted as the traveling speed signal from the cruise control section 35, NO is determined in step S102 in FIG. 4, and the set speed Vs is inputted as the traveling speed signal from the cruise control section 35. Wait until.

The gradual acceleration/deceleration control section 37 determines whether a battery state signal indicating a high load state has been input from the battery monitoring section 36 in step S103 of FIG. When the gradual acceleration/deceleration control unit 37 determines YES in step S103 of FIG. 4, the process proceeds to step S104 of FIG. An acceleration running command or a coasting running command is generated and output to the inverter control unit 38.

The gentle acceleration driving command is a command to gradually increase or decrease the vehicle speed V so that the vehicle speed V falls within a predetermined speed range sandwiching the set speed Vs, as shown in the upper graph of FIG. As shown in the upper graph of FIG. 5, the gradual acceleration/deceleration control unit 37 gently accelerates the vehicle speed V from the set speed Vs from time t0, which is determined to be YES in step S103 of FIG. 4, to time t1. A slow acceleration driving command to accelerate to the upper limit speed V1 of a predetermined speed range is output. Based on this slow acceleration driving command, the inverter control unit 38 issues an inverter drive command to the inverter 12 to control the on/off operation of the switching elements of the inverter 12 so as to increase the power supplied from the battery 11 to the motor 15. Output to. As a result, the electric power supplied from the battery 11 to the motor 15 increases, and the vehicle speed V of the electric vehicle 100 increases. At this time, as shown in the lower graph of FIG. 5, the output current value IB of the battery 11 gradually increases on the discharge side.

As shown in the upper graph of FIG. 5, when the vehicle speed V reaches the upper limit speed V1 at time t1, the gradual acceleration/deceleration control unit 37 issues a coasting command to the inverter so that the vehicle speed V gradually decreases from the upper limit speed V1. It is output to the control section 38. With this coasting command, the inverter control unit 38 controls the inverter 12 so that the output current value IB of the battery 11 changes from the discharging current IB1 at time t1 to the charging current IBc, as shown in the lower graph of FIG. An inverter drive command for controlling the on/off operation of the switching elements is generated and output to the inverter 12. As a result, the motor 15 enters a gentle regenerative drive state, and the battery 11 is charged with a predetermined charging current IBc. Then, the electric vehicle 100 coasts in which the vehicle speed V gradually decreases from the upper limit speed V1. When the vehicle speed V decreases to the lower limit speed V2, the slow acceleration/deceleration control section 37 outputs a slow acceleration driving command to the inverter control section 38 to gradually increase the vehicle speed V from the lower limit speed V2 to the upper limit speed V1. Thereby, the inverter control unit 38 outputs an inverter drive command to the inverter 12 to control the on/off operation of the switching elements of the inverter 12 so as to increase the power supplied from the battery 11 to the motor 15. As a result, the output current value IB of the battery 11 changes from the charging current IBc to the discharging current IB2 at time t2, and thereafter increases as the vehicle speed V increases. Then, electric vehicle 100 accelerates slowly.

In this way, the inverter control unit 38 alternately repeats slow acceleration running and coasting running to increase or decrease the vehicle speed V within a predetermined range, according to the slow acceleration running command and the coasting running command output by the slow acceleration/deceleration control unit 37. The battery 11 is alternately discharged and charged.

The gradual acceleration/deceleration control unit 37 determines whether the battery status signal input from the battery monitoring unit 36 is in a low load state in step S105 of FIG. If the determination in step S105 in FIG. 4 is NO, the process returns to step S104 in FIG. 5 to continue generating and outputting the slow acceleration command and the coasting command. On the other hand, if it is determined YES in step S105 of FIG. 5, the slow acceleration/deceleration control section 37 stops the slow acceleration running command and the coasting running command.

Moreover, when the slow acceleration/deceleration control unit 37 determines NO in step S103 of FIG. 4, it does not generate or output the slow acceleration running command and the coasting running command.

In this way, when the slow acceleration/deceleration control section 37 does not generate and output the slow acceleration running command and the coasting running command, the inverter control section 38 receives the set speed Vs from the cruise control section 35 as a running speed signal. It has been entered. Then, in step S106 of FIG. 5, inverter control unit 38 outputs an inverter drive command to control inverter 12 so that electric vehicle 100 travels at a constant speed of set speed Vs.

If the set speed Vs is inputted as the travel command signal from the cruise control unit 35, the inverter control unit 38 determines NO in step S107 of FIG. 7 and returns to step S103 of FIG. 5. On the other hand, when the variable speed is input as a travel command signal from the cruise control section 35, the inverter control section 38 determines YES in step S107 of FIG. 7, proceeds to step S108 of FIG. 4, and responds to the variable speed. An inverter drive command that changes the vehicle speed V is generated and output to the inverter 12. As a result, electric vehicle 100 follows the vehicle.

If the traveling speed signal continues to be input from the cruise control unit 35, the inverter control unit 38 determines NO in step S109 of FIG. 4, returns to step S102 of FIG. 4, and continues the operation. On the other hand, when the traveling speed signal is no longer input from the cruise control section 35, the inverter control section 38 determines YES in step S109 of FIG. 4 and ends the process.

As explained above, the electric vehicle 100 can maintain a balance between discharging and charging the battery 11 by alternately repeating slow acceleration running and coasting running, so that the input and output of the battery 11 is only on the discharging side. Therefore, the occurrence of polarization of the battery 11 can be suppressed. Thereby, an increase in the amount of heat generated by the battery 11, deterioration of the battery 11, etc. can be suppressed.

Furthermore, when the battery 11 changes from a high load state to a low load state where almost no polarization occurs even if the input/output of the battery 11 becomes only on the discharge side, the electric vehicle 100 can perform slow acceleration running and coasting running. Stops driving and returns to constant speed driving. As a result, smooth constant speed running can be achieved in a low load state.

Although the travel control device 30 described above has been described as storing the map 33 described with reference to FIG. 2 in the memory 32, the present invention is not limited to this. For example, as shown in FIG. 6, a map 34 showing the relationship between the output power value WB of the battery 11 and the load state of the battery 11 may be stored in the memory 32. In this case, the battery monitoring unit 36 calculates the output power value WB of the battery 11 based on the output current value IB of the battery 11 detected by the current sensor 21 and the voltage value VB of the battery 11 detected by the voltage sensor 22. do. Based on the map 34, the battery monitoring unit 36 detects a high load state of the battery 11 when the output power value WB exceeds the first reference value, and detects a high load state of the battery 11 when the output power value WB is smaller than the first reference value. It may also be possible to detect that the high load state of the battery 11 has been canceled and the battery 11 has entered a low load state when the value is equal to or less than two reference values.

Furthermore, although the cruise control unit 35 of the cruise control device 30 has been described as performing follow-up travel control and constant speed travel control, the cruise control unit 35 is not limited to this, and may be configured to perform only constant speed travel control. In addition, in place of the cruise control section 35, an automatic driving device is provided that automatically performs steering, acceleration/deceleration, etc. of the electric vehicle 100, and the slow acceleration/deceleration control section 37 and the inverter control section 38 are controlled by the automatic driving device. When the mode is set, a traveling speed signal may be input from the automatic driving device.

11 battery, 12 inverter, 15 motor, 16 output shaft, 17 gear, 18 transaxle, 19 wheels, 21 current sensor, 22 voltage sensor, 23 V-phase current sensor, 24 W-phase current sensor, 25 resolver, 26 vehicle speed sensor, 30 travel control device, 31 CPU, 32 memory, 33, 34 map, 35 cruise control section, 36 battery monitoring section, 37 gradual acceleration/deceleration control section, 38 inverter control section, 100 electric vehicle.

Claims (4)

An electric vehicle that uses a battery as a power source and a motor as a drive source,
Equipped with a travel control device that adjusts travel speed,
When the traveling control device detects a high load state of the battery while traveling at a constant speed with the traveling speed adjusted to a set speed,
Alternately repeating slow acceleration running and coasting running, increasing/decreasing the running speed within a predetermined speed range sandwiching the set speed;
An electric vehicle featuring The electric vehicle according to claim 1,
The travel control device executes constant speed travel at the set speed when detecting cancellation of the high load state of the battery;
An electric vehicle featuring The electric vehicle according to claim 1 or 2,
comprising a current sensor that detects an output current value of the battery,
The travel control device includes:
detecting a high load state of the battery when the square value of the output current value of the battery detected by the current sensor exceeds a first threshold;
Canceling the detection of the high load state of the battery when the square value of the output current value becomes equal to or less than a second threshold value that is smaller than the first threshold value;
An electric vehicle featuring The electric vehicle according to claim 1 or 2,
a current sensor that detects an output current value of the battery;
A voltage sensor that detects the voltage value of the battery,
The travel control device calculates the output power value of the battery based on the output current value of the battery detected by the current sensor and the voltage value of the battery detected by the voltage sensor,
detecting a high load state of the battery when the output power value exceeds a first reference value;
detecting release of the high load state of the battery when the output power value becomes equal to or less than a second reference value that is smaller than the first reference value;
An electric vehicle featuring